1.\" $NetBSD: getifaddrs.3,v 1.12 2010/03/22 19:30:54 joerg Exp $ 2.\" BSDI getifaddrs.3,v 2.5 2000/02/23 14:51:59 dab Exp 3.\" 4.\" Copyright (c) 1995, 1999 5.\" Berkeley Software Design, Inc. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY Berkeley Software Design, Inc. ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL Berkeley Software Design, Inc. BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.Dd April 21, 2009 25.Dt GETIFADDRS 3 26.Os 27.Sh NAME 28.Nm getifaddrs 29.Nd get interface addresses 30.Sh SYNOPSIS 31.In sys/types.h 32.In sys/socket.h 33.In ifaddrs.h 34.Ft int 35.Fn getifaddrs "struct ifaddrs **ifap" 36.Ft void 37.Fn freeifaddrs "struct ifaddrs *ifp" 38.Sh DESCRIPTION 39The 40.Fn getifaddrs 41function stores a reference to a linked list of the network interfaces 42on the local machine in the memory referenced by 43.Fa ifap . 44The list consists of 45.Nm ifaddrs 46structures, as defined in the include file 47.In ifaddrs.h . 48The 49.Nm ifaddrs 50structure contains at least the following entries: 51.Bd -literal 52 struct ifaddrs *ifa_next; /* Pointer to next struct */ 53 char *ifa_name; /* Interface name */ 54 u_int ifa_flags; /* Interface flags */ 55 struct sockaddr *ifa_addr; /* Interface address */ 56 struct sockaddr *ifa_netmask; /* Interface netmask */ 57 struct sockaddr *ifa_broadaddr; /* Interface broadcast address */ 58 struct sockaddr *ifa_dstaddr; /* P2P interface destination */ 59 void *ifa_data; /* Address specific data */ 60.Ed 61.Pp 62The 63.Li ifa_next 64field contains a pointer to the next structure on the list. 65This field is 66.Dv NULL 67in last structure on the list. 68.Pp 69The 70.Li ifa_name 71field contains the interface name. 72.Pp 73The 74.Li ifa_flags 75field contains the interface flags, as set by 76.Xr ifconfig 8 77utility. 78.Pp 79The 80.Li ifa_addr 81field references either the address of the interface or the link level 82address of the interface, if one exists, otherwise it is 83.Dv NULL . 84(The 85.Li sa_family 86field of the 87.Li ifa_addr 88field should be consulted to determine the format of the 89.Li ifa_addr 90address.) 91.Pp 92The 93.Li ifa_netmask 94field references the netmask associated with 95.Li ifa_addr , 96if one is set, otherwise it is 97.Dv NULL . 98.Pp 99The 100.Li ifa_broadaddr 101field, 102which should only be referenced for non-P2P interfaces, 103references the broadcast address associated with 104.Li ifa_addr , 105if one exists, otherwise it is 106.Dv NULL . 107.Pp 108The 109.Li ifa_dstaddr 110field references the destination address on a P2P interface, 111if one exists, otherwise it is 112.Dv NULL . 113.Pp 114The 115.Li ifa_data 116field references address family specific data. 117For 118.Dv AF_LINK 119addresses it contains a pointer to the 120.Fa struct if_data 121.Pq as defined in include file Aq Pa net/if.h 122which contains various interface attributes and statistics. 123For all other address families, it is 124.Dv NULL . 125.Pp 126The data returned by 127.Fn getifaddrs 128is dynamically allocated and should be freed using 129.Fn freeifaddrs 130when no longer needed. 131.Sh RETURN VALUES 132Upon successful completion, a value of 0 is returned. 133Otherwise, a value of -1 is returned and 134.Va errno 135is set to indicate the error. 136.Sh ERRORS 137The 138.Fn getifaddrs 139may fail and set 140.Va errno 141for any of the errors specified for the library routines 142.Xr ioctl 2 , 143.Xr socket 2 , 144.Xr malloc 3 145or 146.Xr sysctl 3 . 147.Sh SEE ALSO 148.Xr ioctl 2 , 149.Xr socket 2 , 150.Xr sysctl 3 , 151.Xr networking 4 , 152.Xr ifconfig 8 153.Sh HISTORY 154The 155.Nm 156implementation first appeared in 157.Bsx . 158.Sh BUGS 159If both 160.In net/if.h 161and 162.In ifaddrs.h 163are being included, 164.In net/if.h 165.Em must 166be included before 167.In ifaddrs.h . 168